IM-designed Rocket Motor Using a Shape Memory Alloy

摘要

Special design modifications are required to fulfil the requirements specified in IM tests such as Fast Cook-Off (FCO) and Slow Cook-Off (SCO), where the reaction shall not be more severe than a burning (Type Ⅴ reaction). The best solution is, naturally, when the containers for the explosive substances, whether in the rocket motor or the warhead, are opened before the propellant or high explosives charge ignites during testing. The purpose of this work it to show how such a function can be achieved by making the rocket motor housing locking mechanism out of shape memory alloy. The shape memory alloy unit, presently under development and testing, is comprised of a lock-ring between the front closure and the cylindrical midsection of the rocket motor housing. The lock-ring releases its locking function after an increase in temperature, up to a specified temperature, called the activation temperature, has been reached. The presently developed and tested shape memory alloy ring (lock-ring) has an activation temperature of approximately 102℃, which is a suitable level between what is normally required, as a maximum storage temperature, that a weapon system shall withstand and the exterior temperature of the rocket motor housing when a propellant charge of single or double base type ignites during SCO testing. The work began with finding a Shape Memory Alloy (SMA) with a suitable activation temperature as well as fashioning such an alloy as a ring with the correct dimensions. Then the wire must be normalized, and formed into a ring that is then trained such that a shape alteration obtains at the activation temperature. The first part was finished by testing its function in a rocket motor loaded with "mechanical energy" instead of propellant. Finally, a FCO test was conducted where the results obtained were a burning, Type Ⅴ reaction, and two SCO tests were conducted, both with burning, Type Ⅴ reaction, obtaining.